log.LogInformation("########## Starting ##########");
var apiKey = "Send Grid API Key";
log.LogInformation(apiKey);
var client = new SendGridClient(apiKey);
var from = new EmailAddress("email id", "Example User");
var subject = "Sending with SendGrid is Fun";
var to = new EmailAddress("email id", "Example User");
var plainTextContent = "and easy to do anywhere, even with C#";
var htmlContent = "<strong>and easy to do anywhere, even with C#</strong>";
var msg = MailHelper.CreateSingleEmail(from, to, subject, plainTextContent, htmlContent);

string storagefilename = "Storage file name";


WebClient client1 = new WebClient();
Stream stream = client1.OpenRead(storagefilename);
StreamReader reader = new StreamReader(stream);
String content = reader.ReadToEnd();

byte[] byteArray = Encoding.ASCII.GetBytes(content);

log.LogInformation("####### " + byteArray);
msg.Attachments = new List<SendGrid.Helpers.Mail.Attachment>
            {
                new SendGrid.Helpers.Mail.Attachment
                {
                    Content = Convert.ToBase64String(byteArray),
                    Filename = "Transcript.pdf",
                    Disposition = "attachment"
                }
            };

var response = client.SendEmailAsync(msg);

log.LogInformation("####### Mail Sent ###########");

string requestBody = await new StreamReader(req.Body).ReadToEndAsync();